I think the Like button is against Google's DNA which is why all these initiatives seem half assed. Google doesn't want to rely on users to say what they like. Instead Google looks at actual user behavior by examining logs. It's the same reason Google resists limiting or anonymizing logs. It's also the reason Google did the "unthinkable" by combining its cookie with Double Click's - Google derives enormous value by analyzing actual user behavior across both on Google's own sites and across every other site with Google's ads. Asking the user to self report by clicking a button every time seems primitive in comparison and not worth pursuing.